Many circumstances exist wherein a person wishes to couple a flexible hose, such as a flexible air line, to an inflexible coupling, such as a coupling made from steel or brass. These circumstances typically arise in fluid systems that carry a gas or liquid between two points; and fluid systems that employ a gas or air to perform work, such as air brake systems, pneumatic systems and hydraulic systems. One particular circumstance where it is desirable to couple a flexible fluid carrying hose to an inflexible coupling is in the air system of a truck, such as a tractor trailer, or of a railroad car or locomotive.
Large vehicles, and in particular semi-tractors and their trailers, and locomotives and railroad cars use an air system to control braking. In most air brake systems, the air pressure is used to release the shoe of the brake from its engagement with the drum or disk of the brake in order to permit the vehicle to be moved. Most air brakes on trains and trucks are biased with springs or other mechanical means, so that in the absence of air pressure, the shoe will engage the drum (or disk) and thereby place the brake in a "brake on" position, to prevent the vehicle from moving. Air pressure is fed to a pneumatic cylinder within the brake shoe so that when air pressure is applied to the brake shoe, the brake shoe will move away from the drum or disk to disengage the drum or disk, thereby allowing the drum or disk to spin on its axle, thereby allowing the hub and wheel to rotate.
In order to "get air" to the various brake shoes of a multi-wheel vehicle, a large number of air lines must be used. Because the various vehicle components such as the wheels and the frame move in relation to each other, it is desirable to employ a flexible air line to couple the air receiving member (such as the brake shoe) on the wheel to the air provider component (such as a niold mounted on the frame of the trailer). A large number of different types and brands of flexible air lines are currently manufactured and are available from companies such as Gates Rubber, and Dayco Products.
Typically, a coupling is placed on each end of the flexible air hose, to permit the air hose to be coupled to another air system component, such as an air manifold. On a large vehicle, such as a truck, a large quantity of air hoses, and hence a large quantity of air hose couplings are used, typically about 100 or so in a semi-tractor rig.
Known couplings exist that usually include a tube support that is surrounded by a coaxially disposed housing. An O-ring is inserted at the base of the tube support to prevent air leaking therethrough. Couplings of this type have some inherent problems. One problem is the sharp edges on the end of the flexible brake hoses come in contact with the O-rings. This contact can nick or damage the O-ring, thereby creating a leak in the system that causes the system to lose air.
One object of the present invention is to provide a coupling that eliminates the contact between the O-ring and the air hose and which also grips the hose in a manner such that air cannot pass around the hose on its outside or inside.